1. Field of the Invention.
This invention relates to steering of machinery trailers and dollies having wheels that are relatively far behind wheels of a towing vehicle.
2. Relation To Prior Art.
Wheels of machinery trailers that are relatively far behind wheels of a towing vehicle take shortcuts instead of following behind or where desired on turns. Typical are wheels of tandem rake dollies that bypass hay on turns, highway-trailer wheels that run over curbs and industrial dollies that hit corner stacks and structures when their wheels take shorter distances than those of towing vehicles such as various types of tractors and trucks.
There are known trailer-steering means, but none that allow turn-positioning with controllable motors in a manner taught by this invention.
Examples of different but related devices for steering trailing vehicles are described in the following patent documents. U.S. Pat. No. 5,412,929, issued to Urbain et al, described a tandem implement hitch having a hydraulic cylinder expandable between pivotal arms of wheel-turning rods. U.S. Pat. No. 5,404,702, issued to Lewis, described a windrow apparatus for guiding hay into a hay bailer from opposite sides. U.S. Pat. No. 4,166,352, issued to Knusting, described a hay-making machine that was adjustable to land irregularities but not to turns. U.S. Pat. No. 5,231,829, issued to Tonutti, described a rake trolley with width adjustment but not wheel-following turn adjustment. U.S. Pat. No. 5,025,616, issued to Moss, described a side arm for towing a second rake beside and behind a first rake towed by a tractor. U.S. Pat. No. 4,977,734, issued to Rowe et al, described a hydraulically foldable hay rake.
Problems with trailing of wheels of agricultural and industrial trailers and dollies continue to exist.